Bacterial Causes of Empyema in Children, Australia, 2007–2009

Roxanne E. Strachan, Anita Cornelius, Gwendolyn L. Gilbert, Tanya Gulliver, Andrew Martin, Tim McDonald, Gillian M. Nixon, Rob Roseby, Sarath Ranganathan, Hiran Selvadurai, Greg Smith, Manuel Soto-Martinez, Sadasivam Suresh, Laurel Teoh, Kiran Thapa, Claire E. Wainwright, Adam Jaffé , and on behalf of the Australian Research Network in Empyema

Author affiliations: Sydney Children’s Hospital, Randwick, New South Wales, Australia (R.E. Strachan, A. Jaffé); Royal Hobart Hospital, Hobart, Tasmania, Australia (A. Cornelius); Centre for Infectious Diseases and Microbiology, Westmead, New South Wales, Australia (G.L. Gilbert, K. Thapa); John Hunter Hospital, Newcastle, New South Wales, Australia (T. Gulliver); Princess Margaret Hospital for Children, Perth, Western Australia, Australia (A. Martin); The Canberra Hospital, Canberra, Australian Capital Territory, Australia (T. McDonald, L. Teoh); Monash Institute of Medical Research, Melbourne, Victoria, Australia (G.M. Nixon); Alice Springs Hospital, Alice Springs, Northern Territory, Australia (R. Roseby); Royal Children’s Hospital, Melbourne (S. Ranganathan, M. Soto-Martinez); Children’s Hospital at Westmead (H. Selvadurai); Women’s and Children’s Hospital, Adelaide, South Australia, Australia (G. Smith); Mater Children’s Hospital, Brisbane, Queensland, Australia (S. Suresh); Royal Children’s Hospital, Brisbane (C.E. Wainwright)

Abstract

An increase in the incidence of empyema worldwide could be related to invasive pneumococcal disease caused by emergent nonvaccine replacement serotypes. To determine bacterial pathogens and pneumococcal serotypes that cause empyema in children in Australia, we conducted a 2-year study of 174 children with empyema. Blood and pleural fluid samples were cultured, and pleural fluid was tested by PCR. Thirty-two (21.0%) of 152 blood and 53 (33.1%) of 160 pleural fluid cultures were positive for bacteria; Streptococcus pneumoniae was the most common organism identified. PCR identified S. pneumoniae in 74 (51.7%) and other bacteria in 19 (13.1%) of 145 pleural fluid specimens. Of 53 samples in which S. pneumoniae serotypes were identified, 2 (3.8%) had vaccine-related and 51 (96.2%) had nonvaccine serotypes; 19A (n = 20; 36.4%), 3 (n = 18; 32.7%), and 1 (n = 8; 14.5%) were the most common. High proportions of nonvaccine serotypes suggest the need to broaden vaccine coverage.

Empyema in children is a relatively uncommon disease that occurs in 0.7% of children with pneumonia (1).

Many organisms cause empyema in children; Streptococcus pneumoniae is the most common (2–6). Other important causes, which are becoming increasingly frequent in several countries, are methicillin-sensitive Staphylococcus aureus (MSSA) (2,7,8) and methicillin-resistant S. aureus (MRSA). The latter is particularly problematic in indigenous communities (9). Other commonly identified organisms include S. pyogenes, Haemophilus influenzae, Mycoplasma pneumoniae, Pseudomonas aeruginosa, and other Streptococcus spp (10). The identification of causative organisms is usually determined by standard blood or pleural fluid cultures. Cultures are limited in that the yield can be as low as 8% (11), possibly because of prior antimicrobial drug treatment. Molecular techniques, such as PCR, are more sensitive in detecting causative organisms than standard culture (11) but are not routinely employed in laboratories for clinical use.

The 7-valent pneumococcal conjugate vaccine (PCV7) (Prevenar; Wyeth, Philadelphia, PA, USA) was introduced in Australia for immunocompromised and indigenous children <2 years of age in 2001 and was added to the national immunization schedule for all children <2 years in 2005 (www.medicareaustralia.gov.au/public/services/acir/index.jsp

). Of >90 pneumococcal serotypes, the 7 included in the vaccine were responsible for 50%–70% of invasive pneumococcal disease (IPD) in children in most populations at the time of its development (12).

Many reports from around the world suggest an increase in the incidence of empyema in children (1,6,13–19). The reasons for this increase are unknown but may be related to IPD caused by emergent nonvaccine replacement serotypes, particularly serotypes 1, 3, and 19A after the introduction of PCV7 (14–20).

However, this theory is controversial because several studies identified an increase in empyema prevalence before the introduction of PCV7 (5,21,22). Because no Australian data exist on the bacterial causes of empyema, it is difficult to determine whether incidence in Australia is similar to reported trends in North America (14,22), the United Kingdom (5,6,16,18,21), Spain (15,17), and France (13).

The aims of this study were to identify the bacterial causes of empyema in children by using molecular techniques and to assess the efficacy of PCV7 by using molecular typing of invasive pneumococcal disease serotypes. This information may be helpful in deciding which of the newer conjugate pneumococcal vaccines should be introduced into national vaccination programs.

Methods

full-text:
Bacterial Causes of Empyema in Children, Australia, 2007–2009 - Vol. 17 No. 10 - October 2011 - Emerging Infectious Disease journal - CDC

Suggested citation for this article: Strachan RE, Cornelius A, Gilbert GL, Gulliver T, Martin A, et al. Bacterial causes of empyema in children, Australia, 2007–2009. Emerg Infect Dis [serial on the Internet]. 2011 Oct [date cited]. http://dx.doi.org/10.3201/eid1710.101825

DOI: 10.3201/eid1710.101825